Method of making concrete pipe



METHOD OFMAKING CONCRETE PIPE Filed May ll, 1936 gf (l D n INVENTOR ATTORNFXS Patented Oct. 8, 1940 William W. Trickey,

Verona, N. J., assignor to Lock Joint Pipe Company, East Orange. N. J., a corporation of New Jersey Application May 11,

2 claims.

This invention relates to concrete pipe and method of making the same and particularly to improved pipe of the bell and spigot type. Accordingto previous practices concrete pipe of this 5 type is either cast inone piece or is cast in two l pieces, andjffit is usually necessary to perform ,some manual labor before the manufacture of .thepipe is completed. According tothe latter Vpractice the bell is formed by attaching a collar"tothe conduit portionof the pipe, provision having 'been. made in either the conduit portion of the pipe or collar for cementing the two pieces -together.i, Both of the prior methods have been subjected to criticism principally because of `the l'fpossibilityof the production of pipes whichmay embody defects incapable of discovery except cluringuse.v Defectsmay arise because of the fallibility of human workmanship or of materials incident to forming the bell or to securing the bell-forming collar to the conduit portion of the pipe and as the -result of the development of planes of weakness because of shrinkage strains arising during the setting of the concrete particularlywhen the pipe is cast in one piece. `It is among the objects of my invention to provide a method which may be depended upon to produce quantities of pipe of uniform grade and lacking particularly the defects referred to as found in pipes'manufactured ac- 30 cording to methods heretofore followed.

Another object of the invention is to enable the use of a steel bearing ring upon the interior of the bell without vintroducing a faulty condition in the concrete adjacent the ring because peripheral surface of the ring, while at the same time obtaining all the advantagesincident to forming concrete by centrifugal action in the making of the `conduit portion of the pipe.

Another object of the invention is to eliminate uncertainty in the character and strength of the inner region of a concrete pipe at the bell end thereof, and particularly in and adjacent the region of greatest thickness, all to the end of 45 assuring security against leakage or infiltration of ground water and avoidance of undetermin- `able conditions capable of causing weakness.`

Other objects of the invention are to provide concrete pipe and a method of making the same, wherein the interior surface of the collar of the pipe which forms the bell, whether lined with a metallic bearing member or not, is intimately.

bonded to the exterior surface of the conduit portion of the pipe during its manufacture; to

55 provide ,a methodfor engaging the collar to the of improper compactness of concrete against the 1 1936, Serial N0. 79,054

conduit portion ofthe pipe whereby these members are locked against axial displacement, such as might Aotherwise result from a longitudinal thrust on the collar should the bell end of the pipebe hit sufficiently hard when the pipe is 5 being laid; to render impossible any leakage through the joint between the collar and the conduit portion of the pipe; to eliminate the formation of shrinkage strains in the concrete `of either the collar or the conduit portion of the pipe; to eliminate the necessity of reliance upon manual labor for caulking or cementing together the collar and the concrete portion of the pipe; to obtain automatically correct centering of the interior surface of the bell with the cylindrical portions of the pipe; and to improve upon manufacturing eiliciency in the manufacture of this type of pipe whilev obtaining a` pipe which is more reliable and `of a higher grade than those heretofore obtained.

In itsgeneral aspects, my method contemplates rst forming a collar of concrete and then connecting this collar to the conduit portion of the pipe during the production of said conduit portion. The collar may be made in the desired form` and according to any of the well known processes, but an advantage of my method is that it affords a means of assuring the utmost eiilcacy fromthe use of a'steel bearing ring for the bell portion of the pipe. The collar is formed complete in a suitablemold. The collar is then used aspart of a mold in which the `conduit portion of the pipe is to be cast, the mold constituting, when complete, the previously made collar and a rotatable drum for forming the conduit portion of the pipe. `One end wall of the mold is disposed within the collar in such a. position that a portion of the inner contour of the collar serves asal portion of the peripheral wall of the mold. When this mold is filled with concrete to produce the thickness of conduit wall desired, the entire mold is rotated until the concrete forms. Owing to the centrifugal action developed, the concrete is caused to set firmly against the collar and steel bearing ring.. This assures a secure bond between the conduit portion of the pipe and the collar, while at the same time producing a conduit wall which is substantially uniform in thickness and firmly compacted. When the pipe is ready for removal from the mold it 'is ready for use and does not require any additional work for assuring leak-proof conditions between the co1- lar and the conduit portion of the pipe.

Further and other objects of the invention will be hereinafter set forth in the accompanying specification and claims and demonstrated by the drawing which shows by way of illustration a preferred embodiment and the principle of my invention, and what I now consider the best mode in which I contemplate applying that principle. Other embodiments of the invention employing the same principle may be used and structural changes made as desired by those skilled in the art, within the spirit of the appended claims and without departing from the present invention.

Having reference to the drawing: y

Fig. 1 is a longitudinal section of a portion of joined ends of concrete pipes made according to the present invention.

Fig. 2 illustrates a be used for casting the collar.

Fig. 3 shows a section of the mold in which the conduit portion ofthe pipe is cast.

I first completely' finish the collar and then make use of the finished collar in forming the conduit portion of the pipe. The collar may be formed in a stationary or vibrating mold or may be formed by centrifugal action, but when the use of a steel bearing ring upon'the inside of the bell is desired I prefer to use a mold such as illustrated in Fig. 2. The mold has an annular base I which is designed to support the steel bearing ring Il in the position it is to remain as a part of the finished collar. The mold cavity is completed by an outer wall I2 which is supported upon the base Il). The bearing ring II is concentric with the cylindrical portion of the mold and defines a true circular section.

'I'he bottom of the mold forms the end of the collar that is remote from the bell opening and this can be entirely plain if desired but I prefer that it have a projection I9 which is provided with a sloping surface at its outer periphery. The mold is so designed that the sloping surface will be that of a truncated cone having the same axis as the inner and outer cylindrical walls of the collar. The advantage of providing a sloping surface having this relationship to the collar will appear hereinafter in reference to its function in the forming of the complete pipe.

An inner core member I3 is supported upon the upper edge of the bearing ring. In addition to its function as -a guide and core this member has the function of later serving as an element in the molding of the complete pipe. A cover ring I4 is seated upon the core I3. This cover ring is provided with a number of outwardly extending ngers I5 leaving openings therebetween for permitting the introduction of concrete to the mold cavity. The ngers I5 have attached thereto a depending rim I6 which sets upon and overlaps the upper edge of the outer mold wall I2. The mold cover ring I4 has secured thereto a circular plate I1 which covers the central area of the mold above the inner core member I3. Before cover ring I4 and cover I1 are applied, whatever steel reinforcing that may be desired is introduced into the mold cavity. This reinforcing usually takes the form of steel longitudinal bars and encircling bands I8. Rings I4 and I6 and plate I1 are rigidly associated and they provide means for truing up the concentricity and spacing of the inner and outer mold walls.

Fresh concrete is introduced into the mold up to the top edge of the bearing ring and precautions are taken to assure that it is properly placed so that no voids will remain within the finished collar. The type of mold illustrated and mount Athe collar upon type of mold which may complete when end wallsv may be vibrated for th' purpose or the concrete may be tamped by hand. Compactness of the concrete assures a close bond against the outer periphery of the bearing ring and securely attaches the ring to the concrete of the collar. After the concrete has set, the demountable mold parts are removed and the collar is lifted from the base I0.

The collar, together with the core member I3 is then used as a part of the mold in which the conduit portion of the pipe is formed. While this mold may be so made as to be complete in itself and contain the collar, a convenient manner of forming the same is to use a rotatable shell or drum 20 as the main part of the mold one end thereof.

The mold so formed is are in place, Fig. 3. The shell of the mold is cylindrical and is capable of separation longitudinally into several sections for extricating the completed pipe.

One end of the shell 2I against which the collar of the pipe is held. This ring is welded to the shell or is otherwise permanently attached thereto. The ring is provided with two surfaces 22 and 23 against which corresponding surfaces of the collar of the pipe rest. Surface 22 is in the form of a truncated cone having the same axis as the axis of the cylindrical shell 20, and it bears the same relation to radial surface 23 as the corresponding sloping surface at the bottom of the collar mold bears to the adjacent plain surface at the bottom of the collar mold, Fig. 2. Accordingly, the sloping surface and the adjacent radial surface upon projection I9 of the collar conforms exactly with sloping surface 22 and radial surface 23 of ring 2I against which they are brought, with the result that when the collar is properly held in place against ring 2l, the bearing surface of the bell will be concentric with the cylindrical Wall of the mold 20. The centering of the collar is thereby automatically accomplished by the holding of the collar in place against ring 2| of the cylindrical mold. This has the result of eliminating errors which might otherwise occur if it were necessary to rely upon manual adjustment to center the collar in reference to the cylindrical mold. If the collar is not provided with a projection and sloping surface, other means may be resorted to for holding the collar in place, such as, for example, the dogs 25 which are provided for supporting the collar until the same is firmly assembled as a part of the mold.

A number of these dogs are spaced circumferentially about the mold. The dogs are engaged by cap screws 26 which are carried by the ring 2I. One end of each dog rests against the outer surface of mold wall 20 and the other end serves as a support for the collar. Before the position of the collar in reference to the mold is determined by the sloping surface 22, the collar may -be preliminarily adjusted in reference to the tubular wall by the use of screws 26.

The other end of the tubular mold 20 carries a ring 28 having a radial flange 29 which serves as an end wall for forming the spigot end of thel pipe.

Concrete pipe which is designed to withstand pressure is provided with longitudinal and circumferential reinforcing bands which may be assembled in the manner illustrated. If desired some 'of the longitudinal rods 30 may be provided with nuts 3|,

32 at their ends and used to 20 is provided with a ring" support and hold in place the end rings I3 and 29, but these rings may be held in their proper relation in respect to the mold in any other manner as by devices attached to the outside of the mold. The end ring I3 has a flanged lip 33 engaging the end of the collar 24 whereby the collar is maintained in proper position against ring 2| Some of the longitudinal bars 30 are bent inthe manner illustrated at 34 and Welded to the steel ring 35, which is to form the spigot bearing-ring of the finished pipe. Short braces 36 may be used t'o assistin maintaining the spigot ring in its proper position within the mold.

When the mold for the conduit portion of the pipe has been completely formed with the collar 24 and the end ringsA I3 and 29 forming a part thereof, fresh concrete is introduced within the mold as the same is rotated, care being taken to introduce the concrete in sufficient quantity to obtain the thickness of pipe walldesired. Since the wall being formed is of substantially uniform thickness no area of unequal strains will develop as the concrete is setting.

For rotating the mold, the exterior of its wall 20 is provided with rings 31, 31', which carry trunnion rings 3B, 39. These trunnion rings are held in place by bolts 40 and dogs 4|. One trunnion ring rests upon a pair of rollers 42 and the other trunnion ring rests upon a pair of rollers 43, which are motor-driven. The entire mold assembly is rotated until the fresh concrete of the conduit portion of the pipe has been'compacted sufliciently to withstand handling of the mold. When sulicient time has elapsed for this to have occured, the mold is removed from its rollers. When the pipe is removed from the mold the ends of the longitudinal rods 30 which` extend beyond the concrete are cut and the pipe is ready for use.

By rotating the mold as the concrete of the conduit portion of the pipe is setting, the centrifugal action developed causes therformation of a close bond between the fresh concrete and the interior of the collar and the avoidance of any condition likely to cause weakness or looseness between the collar and conduit portion of the pipe.

My method also provides a means of designing the interior contour of the collar to lock or key the collar to the remaining portion of the pipe. As illustrated in Fig. 2, the collar is provided with two non-cylindrical surfaces 44, 45, in the form of truncated cones and a radial surface upon projection I9 which are to be engaged by complementary surfaces upon the conduit portion of the pipe. The surface which is complementary to the radial surface upon projection 46 is part of abutment ring 41, an integral part of the conduit portion of the pipe.

The tubular mold is provided with such gaskets as may be needed to prevent the escape of `fluid concrete and water while the mold is being rotated. In the mold illustrated in Fig. 3 a gasket 48 is provided at the bell end of the pipe between the ring 2| and collar 24 and two gaskets 49 and 50 are provided at the spigot end of thepipe for preventing the escape ofconcrete ingredients about the spigot bearing ring 35 during the centrifuging operation. In referring to concrete I mean such cementitious materials as are cornmonly used in manufacturing water and other fluid conducting pipes.

What is claimed is:

1. The method of making concrete pipe having a collar and conduit portion and metallic bearing ring, which comprises providing the bearing with cylindrical and non-cylindrical portions, casting a collar of concrete outside of the bearing ring and with a tubular portion thereof extending beyond the bearing ring, and casting the conduit portion of the pipelwith a portion of its exterior surface in contact with a portion of the interior surface of the collar including a non-cylindrical portion of the bearing ring and the tubular extension of the concrete of the collar so as to lock the bearing ring to both the concrete portion of the collarand the conduit portion of the pipe.

2. The method of making concrete pipe having a bell at one end which comprises the steps of forming the part which is to constitute the bell portion of the pipe by casting concrete about the exterior of and beyond the end of a metallic bearing ring and in the shape of a collar, and then forming the conduit portion of the pipe by using as part of the mold therefor, a length of the interior contour of the collar including the concrete at the end of the metallic bearing ring and a portion of the bearing ring, with the remaining length of the collar extending beyond the end of the conduit portion of the pipe for serving as the bell.

WILLIAM W. TRICKEY. 

